Scientists create biodegradable sugar cutlery – 05/15/2023 – Science

In a world of growing concern about climate change, more sustainable solutions are always welcome, but for some items it is more difficult to find options.

Although the pollution caused by excess plastic in the world is worrying, the industry is still looking for alternatives for cutlery that are 100% recyclable or biodegradable and maintain the rigidity of plastics derived from petroleum, for example. The main difficulty is being able to reproduce the physical properties of the material, normally not achieved in paper derivatives or recyclable compounds.

But researchers from the Micron School of Engineering and Materials Science, at the University of Boise, in Idaho, in the United States, have developed a sugar-based compound that can be used in the manufacture of cutlery, disposable materials and decorative objects and that is 100% biodegradable.

The study was published in the specialized journal Sustainable Chemistry & Engineering, of the American Chemical Association (ACS, its acronym in English).

The composition has a culinary item that is well known in the world of confectionery, isomalt, a type of low-calorie sugar used to decorate sweets and cakes. Isomalt has the main characteristic of being moldable at high temperatures.

With that in mind, scientists sought to use isomalt to manufacture cutlery and other rigid objects.

Like all sugar, however, isomalt can suffer from high humidity and temperature, and melt. To get around this problem, a mixture of wood dust and sawdust prevented the objects from melting and deforming at room temperature. For disposal, just break the cutlery and dissolve them with the help of water.

According to Scott Phillips, engineer and senior author of the study, the use of isomalt makes it possible to make the first complete cycle recycling system for disposable cutlery.

“Unlike other disposable plastic cutlery where recycling cannot occur in full cycle [porque são produzidos com um conjunto variado de plásticos] or biodegradable paper cutlery [que podem levar até dois anos para decompor na natureza]isomalt, when broken, loses its rigid characteristic and can be easily dissolved in water”, he said.

According to the experiment, isomalt crystals first need to be heated to a temperature above 170°C to arrive at an amorphous material. Afterwards, they are taken to cool at room temperature and, at this moment, the other additives, such as wood dust and sawdust, are added and again it is heated to an average temperature of 140ºC.

The mixture is then shaped to form small balls, or “pellets”, which can be melted into the shape of the desired object. It is still possible to recover isomalt and other compounds in a recycling process, heating the material to a temperature of approximately 50ºC, thus returning to the pre-mold stage, which makes it possible to reuse the ingredients.

Concentration is very important to obtain good resistance and durability of the material. The researchers tested several proportions, but those that showed the best combination of strength and flexibility were with a maximum of 25% to 30% of cellulose and wood compounds mixed with the isomalt crystals.

“One problem, of course, is that sugar has low resistance to moisture and contact with liquids, which we were able to overcome in the experiment by adding a thin coating of biodegradable and water-resistant resin,” said Phillips. “This layer helps sustain wear temporarily in wet conditions or even submerging in water without dissolving the material.”

According to the authors, one of the problems of the plastics industry is that it produces materials with a possible prolonged use and which are often discarded after the first or second use. As isomalt production already exists all over the world for confectionery demand, scaling up would not be a problem.

The solutions for a more sustainable life certainly involve several substitutions in people’s daily lives, some easier, others more difficult. It is up to us to decide which choices we make with more awareness, thus avoiding the largest production of garbage and consumption of non-renewable resources on the planet, propose the scientists.

“Isomalt is easily recyclable and the process can be repeated several times, without loss of mechanical properties. While recycling would be ideal and even preferable, we know that many products are thrown into the environment. The accumulation of isomalt in nature, however, poses no risk, since it dissolves in sugar and biomass”, they conclude.